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Year 9 Circumference and Area of Circles Worksheet — Level 3 — Practice Set 3 — Answers

Answer sheet with worked solutions for the Year 9 area & perimeter worksheet.

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Success TutoringWorksheetsAnswer sheetYear 9 · Mathematics · Area & Perimeter

Year 9 Circumference and Area of Circles Worksheet — Level 3 — Practice Set 3 — Answers

Show your working. Use the π button on your calculator and round to 1 decimal place unless told otherwise.

1.A circle has a diameter of 14 cm. Find its area, correct to 1 decimal place.

Answer: 153.9 cm2

  1. r = 14 ÷ 2 = 7 cm
  2. A = π × r2 = π × 72 = π × 49
  3. ≈ 153.9 cm2
2.Find the area of a semicircle with a radius of 3 cm, correct to 1 decimal place.

Answer: 14.1 cm2

  1. A = ½ × π × r2 = ½ × π × 9
  2. ≈ 14.1 cm2
3.A circle has a circumference of 26π cm. Find its radius and its area (leave the area in terms of π).

Answer: r = 13 cm; A = 169π cm2

  1. C = 2πr, so 2πr = 26π
  2. r = 13 cm
  3. A = πr2 = 169π cm2
4.A circle has a diameter of 12 cm. Find its area, correct to 1 decimal place.

Answer: 113.1 cm2

  1. r = 12 ÷ 2 = 6 cm
  2. A = π × r2 = π × 62 = π × 36
  3. ≈ 113.1 cm2
5.Find the area of a semicircle with a radius of 5 cm, correct to 1 decimal place.

Answer: 39.3 cm2

  1. A = ½ × π × r2 = ½ × π × 25
  2. ≈ 39.3 cm2
6.A circle has a radius of 14 cm. Find its area, correct to 1 decimal place.

Answer: 615.8 cm2

  1. A = π × r2 = π × 142 = π × 196
  2. ≈ 615.8 cm2
7.Find the area of a semicircle with a radius of 8 cm, correct to 1 decimal place.

Answer: 100.5 cm2

  1. A = ½ × π × r2 = ½ × π × 64
  2. ≈ 100.5 cm2
8.A circle has a circumference of 18π cm. Find its radius and its area (leave the area in terms of π).

Answer: r = 9 cm; A = 81π cm2

  1. C = 2πr, so 2πr = 18π
  2. r = 9 cm
  3. A = πr2 = 81π cm2
9.Find the area of a semicircle with a radius of 6 cm, correct to 1 decimal place.

Answer: 56.5 cm2

  1. A = ½ × π × r2 = ½ × π × 36
  2. ≈ 56.5 cm2
10.A circle has a radius of 15 cm. Find its area, correct to 1 decimal place.

Answer: 706.9 cm2

  1. A = π × r2 = π × 152 = π × 225
  2. ≈ 706.9 cm2
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